The present invention relates to the general field of rotor blades of a turbine engine, and more particularly to rotor blades having a wake that impacts against an aerodynamic surface downstream.
In known manner, such a configuration is to be found in numerous propulsion systems, e.g. between the upstream and downstream rotors of a pair of contrarotating propellers, or of a contrarotating fan of a turbojet, between a propeller and a wing, or between a propeller and the compressor of a turboprop, or between the fan and the outlet guide vanes (OGVs) or between the fan and the compressor of a turbofan, or between the rotor and the pylon of a propeller or of a pair of propellers of a turboprop installed at the rear of the fuselage.
Conventionally, the wake from the rotor impacts against a downstream element after a constant time interval. Nevertheless, as shown in FIG. 1, which shows interaction between the blades 10 of a fan rotor and an OGV 12, all of the blades generate identical wakes 14 that present a constant distribution 16 in azimuth. This feature is troublesome since it causes energy to be concentrated at a single frequency, thereby giving rise to engine noise having a single spectrum line 18, referred to as an interaction line, as shown in FIG. 2.